This patch introduces a notification mechanism that aims at recomputingmsgmni each time an ipc namespace is created or removed.

The ipc namespace notifier chain already defined for memory hotplug managementis used for that purpose too.

Each time a new ipc namespace is allocated or an existing ipc namespace isremoved, the ipcns notifier chain is notified. The callback routine for eachregistered ipc namespace is then activated in order to recompute msgmni forthat namespace.

+ /*+ * msgmni has already been computed for the new ipc ns.+ * Thus, do the ipcns creation notification before registering that+ * new ipcns in the chain.+ */+ ipcns_notify(IPCNS_CREATED); register_ipcns_notifier(ns);